The present invention relates generally to polymeric coated wear surfaces, and particularly to wear surfaces in a submergible pumping system in which a polymeric material, such as a PEEK composite material, is bonded to the wear surface.
Pumping systems, such as submergible and horizontal pumping systems, are utilized in pumping oil and/or other production fluids from producing wells. A typical submergible pumping system, for example, includes components, such as a motor, motor protector and a centrifugal pump. Each of these components has moving parts that are subject to wear. This is particularly true in the relatively harsh downhole environment in which many submergible pumping systems are used.
A variety of surfaces, such as thrust bearing surfaces in the motor protector and/or centrifugal pump are subject to substantial wear. Similarly, other surfaces in the centrifugal pump, such as the impeller and diffuser vanes, the backwash area on the diffuser, impeller skirt, impeller balance ring, the diffuser wall, the diffuser bore and the hubs of the impellers are susceptible to wear. This is particularly true due to grit, such as sand, that often is found suspended in the production fluid.
Attempts have been made to provide a coating on the components at some of these wear areas. For example, thrust bearings have been produced in which the thrust bearing pads have a layer of PEEK material molded over the bearing surface of the pad. However, this molding process is relatively expensive and not conducive to coating many surface areas, such as the surfaces along the inside of a radius or diameter and other surfaces with complex shapes.
Also, centrifugal pumps have incorporated wear rings on the impeller skirt and balance ring. Typically these rings are made of a more wear resistant material, however they can be fabricated of the same material as the stage. Most recently, carbon fiber reinforced PEEK rings have been fabricated for use as wear rings. These wear rings range in thickness and size depending on the centrifugal pump, however the wear rings must be of sufficient cross sectional area to withstand the physical stresses which tend to separate the wear ring from the impeller. Such wear rings typically are held in place by an interference fit which places the ring in tension. Sometimes, wear rings are retained with an adhesive bond or welding.
Having a process by which a polymeric material, specifically a PEEK composite material, could be applied to a wide variety of wear surfaces in a pumping system would be advantageous in reducing component wear. For example, it would be advantageous to allow for direct application of a bonded wear surface of PEEK to replace the common practice of mating a machined wear ring of PEEK with a machined impeller. By direct application of the PEEK wear surface, there is a greater flexibility in selecting the thickness and size of the wear surface.
The present invention features a method for protecting wear areas on internal components used in a production fluid pumping system. The method comprises. providing a PEEK composite material in powderized form. The PEEK composite material is then applied to the internal component by heating the PEEK composite material and propelling it against the internal component.
According to another aspect of the invention, a fluid pumping system is provided. The pumping system includes a plurality of wear areas, each having a metal substrate coated by a bonding layer. A surface wear layer is deposited onto the bonding layer via a multiplicity of molten platelets that form the surface wear layer upon solidification. The surface wear layer comprises a PEEK composite material.
According to another aspect of the invention, a centrifugal pump utilizes at least one diffuser and at least one impeller to create a fluid flow. A plurality of PEEK composite areas are disposed on mating surfaces of the diffuser and impeller to reduce wear due to fluid erosion, sliding surface friction and/or three body wear at that particular area. Each PEEK composite area comprises a layer of PEEK composite bonded to at least one of the diffuser or the impeller.
According to a further aspect of the invention, a thrust bearing is provided for use in a component of a pumping system. The thrust bearing includes at least one thrust pad comprising a substrate pad, typically made of a metal material. A PEEK composite layer is formed on the substrate pad by a multiplicity of PEEK composite particles forced together under high velocity at a temperature at least as high as the melting point of the PEEK composite material.